}
  }

  private static class StandardBaseEncoding extends BaseEncoding {
    final Alphabet alphabet;

    @CheckForNull final Character paddingChar;

    StandardBaseEncoding(String name, String alphabetChars, @CheckForNull Character paddingChar) {
      this(new Alphabet(name, alphabetChars.toCharArray()), paddingChar);
    }

    StandardBaseEncoding(Alphabet alphabet, @CheckForNull Character paddingChar) {